Watch YouTube is my answer. I spent HOURS watching YouTube videos before I made the purchase and they helped me avoid problems and find the car for me. Coding the car so that I could turn the REX on below 75% battery was a BIG one because I had to drive my car 225 miles to get it home. I struggled charging during the trip, but the REX coding saved the day.
I recommend these channels:
SimpleCarGuy - he bought a 2014 at auction and did a ton of things to it.
Wisely Automotive - he owns an EV dealership in the UK. Excellent technical videos.
Funcentric - The i3 is not his main topic, but does a three-part "boot camp" on i3 ownership.
bmwi3diy - I learned a TON from this guy. It really helped me enjoy the car. He does a multi-part series on i3 Secrets & Hidden Features that is very helpful for new owners.
